RFR: JDK-8192876: MacOS build fails intermittently after JDK-8139653

[Tim Bell]

Erik:

> After my fix for linking with freetype, the build has started failing
> intermittently. This is caused by a closed library using the
> BUILD_LIBFONTMANAGER variable as prerequisite, but because of my change
> in JDK-8139653, this variable is no longer valid for that. In this fix,
> I restore BUILD_LIBFONTMANAGER to a valid prerequisite for libraries
> that need to link to it.
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8192876
>
> Webrev: http://cr.openjdk.java.net/~erikj/8192876/webrev.01/

Looks good.

Tim